Correctly add decision reason to transaction

src/Composer/DependencyResolver/Transaction.php

@@ -79,6 +79,7 @@ class Transaction
 
         foreach ($this->decisions as $i => $decision) {
             $literal = $decision[Decisions::DECISION_LITERAL];
+            $reason = $decision[Decisions::DECISION_REASON];
             $package = $this->pool->literalToPackage($literal);
 
             if ($literal <= 0 &&